Cable coating mechanism



H. a DONOVAN CABLE COATING MECHANISM Filled zsept. 20, `19259 VINVENTOR Jan. 14, 1941.

H0 Ward Daum/an j f ATTORNEY Patented Jan. 14, ldt

notturno stares PTNT @LQFQ CABLE con'rrNG monanrslvr Application September- 20, 1939, Serial No. 295,719

3 Claims.

This invention relates to coating insulated electric cables, and more particularly to an improved device for securing uniform coatings on insulated electric cables and the like.

Heretofore, it has been customary in applying coating compositions to insulated electric cables and other strand-like base members to pass the cable through a vessel containing a coating material which adheres to the surface of the cable, and then through a` stationary die, rubber or felt wipers, wiping rolls or the like to remove the surplus. In this process the coating is often unevenly applied to the base member. In many instances the cable or other base member is practically bare at intervals, because of the difficulty in centering the coated cable as it passes through the stationary die or because of non-uniformly worn rubber or felt wipers. Another difliculty encountered has been that the coating material works up through the die, and is thrown out at the surface. The older devices are also particularly incapable cf proper application of aqueous emulsion type coatings.

The improved device, as described hereinafter, 5 avoids the defects of previously available apparatus and affords a coated product of decidedly better quality.

This invention has as an object the provision of a device for obtaining coatings on insulated electric cables and the like which is characterized by improved mechanical operation. Another object is the provision of a device for use in connection with coating cables and the like, whereby a more continuous and uniform coating 5 is secured. A further object is the provision of a device which may convenientlyJoe employed in connection with applying lacquers and enamels or aqueous emulsions of such compositions to electric cables and other strand-like base members. Other objects will become apparent as the description of the invention proceeds.

These objects are accomplished by means of a device comprising a rotary unit including at least one die member, which may be caused to rotate at high speeds, through which the coated insulated electric cable or similar base is passed during rotation of the unit.

In the drawing the single ligure represents a sectional view of the apparatus of the invention.

In the figure, I represents the wire or cable to be coated; ll is a vessel which contains the coating varnish I3. These elements may be of` is provided with a hole 2 which admits the wire to be coated. This die is also provided with threads which screw into a housing It and is also recessed at a larger diameter than the hole meeting the wire. The recess is shown as i8 and is also provided with a spring I5 which 5 y tom end is slightly larger than the top end. l5

At the other end of the shaft a similar housing Il is provided with a die l and a spring l5 substantially the same as that at the lower part of the motor shaft. 1

In the operation of the machine the wire I0 20 passes' downwardly around a. pulley through a bath of the insulating enamel i3 and then passes upwardly through the hole 2 and the spring l5 which tends to wipe off the surplus of the coating. The shaft of the motor l2 together with 25 the housing t revolves at the usual speed of the motor, that is, about 2000 R. P. M. The wire passes upwardly through the tapered hole 3 which tends -to place the composition under some pressure against the wire, thereby filling 30 any uneven spots or imperfections in the wire. The surplus composition is again removed by the upper die I6 and spring l5. vIt emerges from a device through the hole shown as 2.

A modification of the apparatus may be made 35 in which the shaft l2 rotates in bearings and which is provided with a pulley driven by outside means, all of which is not shown in the drawing since this will be apparent to those skilled in the art. The structure illustrated 4o has the advantage that it is compact and may be fastened to a wall and take up a relatively small space.

In any such modification of the invention, 45 however, the shaft between the dies is preferably slightly larger than thedies, on the order of about 512' greater in diameter and is preferably tapered slightly toward the top to facilitate movement of the surplus coating downward 50 for return to the coating bath.

Although the preferred embodiment of the invention as illustrated provides for the operation of thel rotary unit or die member in the vertical plane, satisfactory results can likewise 55 l be achieved when the device is constructed off the vertical. including a horizontal plane.

'As indicated, the device is vconstructed so as to permit its use' with different dies which mayj be readily changed to accommodate .cables of different diameters or to meet any particular y coating thickness requirement.

comprises two dies joined at each end of the tubular, shaft but the use of a single rotating die properly mounted on a rigid structure' or affixed at the base of a conventional or modined drying tower and rotated by any convenient y means is also considered within the purview ofV tinguished from previously available cable coat- .ing apparatus in that it may be successfully employed in coating such bases with aqueous 'emulsion compositions. The following example illustrates one composition of this type whichv was successfully used. However, the utility of the device is not in any way limited to this composition or type of composition since it may be employed with diverse coating compositions including the conventional solventy type cable coating compositions or with solventless enamels.

The following example illustrates `an.,emulsion which operates satisfactorily without modification.

Example 1 Percent Cellulose nitrate (visc. 10-20 Hercules) 22.0

Water 9.3 Tricresyl phosphate 23.0 Butyl alcohol '7.5 Butyl acetate 18.5 Xylene 5.0

Sodium lorol sulfate 0.2 Animal glue-.. 0.5 Water 2.0

Water 12.0

'rms emulsion fwas applied to' an insulated electric cableV designated I in the drawing by passingit through the emulsion composition l 3 in the vessel IlY and thenl through the rotary unit including 'die-.l and the bored motor shaft 3, the

unit, meanwhile,` beingrotated at about 2000 V. P. M. The coated cable was then passed into The preferred embodiment of the invention a conventional drying tower heated to a temperature of about 85` C. where the coating was dried.

Theresulting iinish was unusually uniform with no "skips or bare areas and was quite acceptablel inv all respects. If desired. a plurality of coats may be applied in the same manner. How- -.ever, with successive coats it is necessary to substitute slightly larger die members to make a1- lowance for the increased size of the cable as caused by the thickness of coating.

'I'he improved device,`such as illustrated in Figure 1,-is preferably rotated at a speed of approximately 2000 R. P. M. Depending on the thickness of coating desired and the consistency vof the coating material, a speed of about 1000 to 4000 R. P. M. may be employed. The size of the cable to be coated determines the diameter of the bore of the die. An allowance of about .002" to .003" ls permissible between the surface of the cable and the wall of the bored shaft. The coating mechanism described herein may be utilized for coating high and low tension cables, other insulated electric conductors such as radio wire, fish lines, tennis racket strings. fibre cord and the like.

The new apparatus affords several operating economies in coating electric cables and similar i bases. The timeand expense involved in replacing worn wiping equipment are eliminated. 'I'he operation of the devicev provides for the return of the surpluszcoating material to the coating vessel. .Theiinallproduct is characterized by an extraordinarily smooth, uniform coating with no skips or thinly coated areas. The new device also permits thev use of coatingsin aqueous emulsion form, a type of coating which is not operative with most previously available equipment.

I-t is. apparent that many Widely different embodiments of this invention may be made without departing from the spirit and scope thereof; and, therefore, it is not intended to be hunted except as indicated in the appended claims.

I claim:

1. Apparatus for coating electric cables and the like which comprises an electric motor having a hollow shaft, means for applying a liquid coating composition to the cable to be coated, and two dies attached to the opposite ends of the said motor shaft, and means for passing the coated wire through the said dies and hollow shaft.

2. The apparatus of claim l in which the die encases a helical spring wiper.

3. Apparatus of claim 1 in which the axis of the rotary unit is vertical.

HOWARD G. DONOVAN. 

